As a rattlesnake researcher, I have found that these animals are much
different than the media portrays them to be. For example, many people
are unaware that they have docile temperaments, and exhibit maternal
care and kin recognition behaviors. Rattlesnakes are also one of the
most abundant predators by biomass in their environment, making them an
integral part of the ecosystem. Their population declines could have
cascading effects, which may drastically change food web dynamics. Thus, it saddens me that an
"educational" channel like the Animal Planet would promote the slaughter
of such beautiful and important creatures. If you have not already done
so, please sign the petition to stop their show, Rattlesnake Republic,
which glorifies hunters who kill rattlesnakes for profit. It serves no
other purpose than to miseducate the public, propagate fear, and deter
conservation efforts on those species currently in decline. Please sign the petition to cancel this show here.
My life has been crazy busy: finishing up the field season, travelling to Vancouver, and moving to San Diego from Davis. Now that I am finally settling down, I found the time to travel to BORR last weekend to check on the snakes and collect venom (we are collaborating with the Gibbs lab to examine individual and seasonal variation in venom composition). However, after two days of searching, we found ZERO snakes. Zip, nada, nothing! It's not like we were looking for snakes randomly. I have 20 of them with implanted radio-transmitters--this means I can track their exact location. However, after hours of tracking and re-tracking and re-tracking, NONE were on the surface. What the *bleep* are they doing?!
Northern Pacific Rattlesnakes mate bimodally. This means that they have two mating seasons: the spring and the fall. I was hoping to see mating activity last weekend, but instead I saw nothing. However, I did track several females to the exact same burrow as males. I found many male-female pairings and I found one two male-one female cluster. Although I could not see the snakes, I suspect they could be mating in shelter.
I also noticed that most of my snakes were hidden within rocky outcrops. This is strange for my site because there are very few of these. In the summer, snakes mainly hide in abundant squirrel burrows, but I did find that they tended to overwinter in the outcrops. This makes me wonder if they are moving to their overwintering sites early. Normally overwintering ("hibernation") begins in November and lasts through March. Check out the nice outcrops the snakes were in:
One snake in here:
One male and one female shacked up here:
TWO males, one female here:
The weekend wasn't a total loss though. We saw a nice little spider crossing the road and found that one of our females gave birth:
Tarantula!
A little baby outside its den:
Who knows what the snakes were up to? Maybe it was just too hot of a weekend. So much for me collecting venom...
After seven weeks of grueling field work, we have completed this year's data collection on squirrel-snake interactions. This year was much different than last year--the lack of rain led to less overall vegetation cover and what appeared to be reduced snake activity. Last year we recorded several strikes on squirrel pups, but we only saw a few this year. In fact, by the time we left BORR, most of the snakes had lost body mass instead of gaining it, suggesting that they still had not successfully found a meal. Eating seems like such a simple task to us, but for snakes, capturing prey is harder than it looks. It may take weeks before a snake is able to eat--snakes must complete three steps to successfully consume a meal: (1) strike and hit the prey, (2) envenomate the prey, and (3) relocate the prey after envenomation.
Our video recordings have shown that snakes can falter at all three steps. We have seen many instances where a snake clearly strikes and hits a prey item, and yet it never searches for it. We suspect that the snake was unable to successfully envenomate the prey, so it was not worth its time to go look for it. We have also seen snakes strike and kill prey, but unable to find the prey afterward. This year we found a squirrel pup that had been envenomated; still alive, but clearly succumbing to the venom. Upon our arrival, the pup ran into the burrow where the snake that struck it was. The snake emerged an hour later looking for the pup. It moved in and out of a triangle of three burrows (NOT the burrow that the pup was actually in) for a total of 5 hours searching for the dead pup. It never found it. It is so interesting that a snake could wait for days just to strike a squirrel and yet, even when it does, it may not relocate it afterward.
Teetee, male northern Pacific rattlesnake, in ambush right outside a squirrel burrow. It took him 13 days to get a meal.
Although it is tough being a foraging snake, feeding events still occur. Our most exciting feeding event this year was accomplished by Greeata, a female northern Pacific rattlesnake. It only took Greeata 2 days to successfully consume a squirrel pup. Initially, she chose several ambush sites outside of pup burrows at the base of a tree. However, in the end, she managed to strike a pup while underground beneath a log. While radio-tracking her, we found a dead squirrel pup just outside her burrow. We set up a camera on it, and lo and behold two hours later she emerged to consume it. It was quite an exciting day. Below I have posted a video of her selecting her ambush sites, and some pics of her consuming her big meal. Enjoy!
Greeata pulling the dead pup into the shade of her log
She swallows the pup at the entrance of her log burrow
Sorry for the delay in posting...I can't believe we are already in our third week of the field season! This year has been a blast so far. I have seven awesome undergraduate interns who are dedicated and hard-working-- working 12 hours a day, 6 days a week; tracking snakes, trapping squirrels, filming interactions, and running behavioral experiments (whew!). Our lab is able to capture rarely seen rattlesnake behaviors because we put in crazy amounts of effort, something I think few researchers are willing or unable to do. Our hard work often leads to rewarding surprises when we catch glimpses of animal interactions or behaviors that are rarely seen (and sometimes NEVER seen before). The fact that we see behaviors that have never been described highlights the importance of observational and basic ecological studies. Most researchers believe that the best science comes from empirically testing hypotheses by manipulating variables--but if we still don't understand how an organism interacts with its environment and other animals, how can we form hypotheses about it? I find it unfortunate that observational studies are not as valued as empirical studies; just my two cents.
Anyway, I have posted some pics of the new Crotalus Crew hard at work, and some of the rewarding things we have seen in the field. Enjoy!
Trevor and Rey stake out next to a squirrel colony (I hope they capture awesome interactions!)
Erynn, using radio-telemetry to track one of our snakes:
Tara, checking the body temps of our study snakes:
Mark, taking a pic of the king snake he found:
Me, implanting a snake with a radio-transmitter:
We found out that two-year-old rattlers can eat squirrel pups. Check out that bulge!
A male Bullock's Oriole hovering to the left of its nest:
Our most rewarding surprise yet! Two California king snakes mating on the dirt road:
Spring is in the air. Spring is a special time for snake enthusiasts because it marks the start of the rattlesnake active season. Rattlesnakes spend the winter in "hibernation" where they den in burrows or rocky outcrops. Some species of rattlesnake (for instance, Timber Rattlesnakes) overwinter in large communal dens with dozens of individuals sharing the same space. It was recently discovered that den-mates are often kin, and that rattlesnakes may preferentially den with their relatives. The species I study, the Northern Pacific Rattlesnake, is not known to den communally although we did see at least 6 snakes over-winter in the same rocky outcrop this year.
Spring also marks the time when neonate rattlesnakes become young-of-the-years. Female rattlesnakes give birth (yes, livebirth) during the fall before they retreat to their winter dens. The babies they produce are called neonates and in order to survive the winter, the neonates must find a meal or they will starve to death. Neonates, which are about the size of a pencil, are too small to consume squirrels, but they will eat insects and lizards. After the neonates eat, they will over-winter together at the site where they were born. These babies then emerge in spring and disperse from their natal homes. During the first year of their lives, baby rattlesnakes are called "young-of-the-years." Their rattles will consist of one natal button at the very tip and a couple of segments below to signify their shedding events. Once these individuals reach two-years of age, they will be called juveniles.
I have been traversing the hills of BORR to capture adult snakes for our upcoming field season (we start next Wednesday!), and I can't help but notice the freshness of spring. Babies are out and about. This little guy (or gal?) we found coiled in the grass next to a large rock. Perhaps, this was its overwintering site?
..and it's not just rattlesnakes that are producing babies. Last week I found a nest with a baby Red-tailed Hawk. Hopefully, the mother refrains from eating any of our study snakes!
In October I found a burrow where neonates had recently been born. I check in on the babies every time I visit the field site. I saw a total of four neonates in the fall (but the mother could have given birth to more), but only one remained when I returned this spring. Either the others were hiding in the burrow or they did not make it through the winter. By now, that one neonate has dispersed...I hope it is doing well.
Here is a video of the neonates moving about their burrow after I first found them in October. The video shows how small the neonates are compared to adult rattlesnakes (the burrow is about the size of a tennis ball and the neonates are about the size of a pencil). Although the video is long, if you are patient you will see that one neonate spends more than 10 minutes exploring the area around its home burrow (it emerges at 1:05 on the video, and the video is sped up to 3-4x for the sake of time). It flicks its tongue in and out as it moves about, presumably picking up chemical cues from its environment. Will it use these cues later in life to navigate back to this burrow next winter?
When multiple species of snake live in the same habitat, how do they interact? Do they communicate with each other? At the Blue Oak Ranch Reserve where human presence is greatly reduced, snake diversity is high and many species occur at high population densities (see species accounts one and two). Our cameras have captured a few rattlesnakes investigating other species of snake. On June 22, Mace Windu, a male Northern Pacific rattlesnake interacted with a king snake and a gopher snake (at separate times). Below are recordings of these interactions (you may want to watch on YouTube to view better video quality).
A king snake bumps into Mace while slithering through the grass. Mace is sitting in ambush in the shadow as the king snake moves through the grass. The king snake retracts its head after it realizes that a rattlesnake is there. It quickly flees and Mace extends his head, as if curious.
A couple of hours later, a gopher snake runs into Mace. The camera is not directly pointed at Mace, but he is partially visible resting in the shade of a rock. A gopher snake moves toward Mace and stops once it realizes that a rattlesnake is there. It quickly takes off, and Mace extends his head and body toward the gopher snake. Is Mace just curious or is he communicating with the gopher snake?
These recordings make me curious about snake-snake interactions:
How often do different species of snake interact, and when they do, what are the nature of these interactions?
Can different species of snake communicate with each other?
King snakes are predators of young rattlesnakes, but how do they interact with adults like Mace?
At BORR, many species of snake live in the same habitat and must interact in some way. Our cameras have been catching glimpses of these interesting snake-snake interactions so hopefully with more video footage we can learn more about them!
Over the past couple of weeks our research has been featured in several news articles (Time, MSNBC, Huffington Post, Fox News), but the article in the San Jose Mercury News is by far the most informative and scientifically accurate. The reporters came out with me last Monday as I searched for snakes for the up-coming field season. They were very excited to learn more about rattlesnakes and the research that is being performed in their own backyard. Check it out!
Below is an awesome screenshot from one of our field recordings. In it, Greeata, a female rattlesnake strikes at an adult squirrel that has been harassing her for the past two minutes. The blue arrow is pointed at Greeata's open mouth as she lunges her head out of the log. The orange arrow is pointed at the squirrel's head as it dodges the snake strike.
This screenshot is intriguing because we rarely observe strikes on squirrels that are actively harassing snakes. This is because squirrels are more likely to evade a strike when they are aware of the snake's presence and snakes don't want to waste time and energy on a strike that will be unsuccessful. This poses the question, why did Greeata strike at this squirrel? Was it a defensive strike rather than a predatory strike? She should have known her strike would be a miss and saved it for another day. One aspect of rattlesnake behavior that I am particularly interested in is the inter-individual variation in strike reactivity. There may be a continuum of behavioral types where some individuals are more judicious, strike less often, but have better strike accuracy while others are more reactive, strike more often, but have less strike accuracy. I hope to capture more snake strikes to analyze this fascinating aspect of rattlesnake hunting behavior.
Last month I was asked to write a guest article for Hizook.com, a robotics website run by postdoc Travis Deyle (Duke University). He was excited because he had just read an article in Robotics and Automation magazine written by the collective minds who developed RoboSquirrel. In his words, he had "never even considered using a robot to research animal behavior" because it was so far removed from what he normally does as a robotic engineer. However, biorobotics have been in the behavior business for decades starting with crude models of honey bees in the 1980s. Today with advancements in technology and decreasing costs scientists are able to collaborate with engineers to develop more sophisticated robotic models, and test hypotheses that were once impossible to test empirically. RoboSquirrel has allowed us to do just this. We can experimentally test the function of squirrel tail-flagging by manipulating the robot's 'behavior', something that could never be done with a live squirrel. For more information on RoboSquirrel and links to other animal robots, check out my guest article on Hizook. Also, check back regularly on Strike Rattle & Roll because RoboSquirrel 2.0 will be deployed this May and RoboKangarooRat trials will commence later this summer.
Our research relies heavily on wireless network security cameras, which we use to record natural animal behaviors. This makes our study unique in that we have hours and hours of video footage of snake behaviors without the interference of human presence. I like to view our work as peering into a short segment of the animal's life which would be impossible to observe otherwise. We have started a lab YouTube channel to propagate our remarkable findings. Below are some examples:
Our cameras are especially useful in capturing rarely observed strikes and our recordings have revealed that snakes in the wild are not as successful at striking prey as they appear to be in the lab. Wild rodents (unlike lab rats) are actually very good at dodging strikes in a split second, foiling snake hunting attempts. Thus, rattlesnakes may be very judicious with their strikes because missing could be costly to the snake (the snake is revealing itself to predators and other prey) See the video below.
Normally rattlesnakes strike prey and release to prevent self-injury from the struggling prey. This is why venom is handy--it kills the prey, allowing the rattlesnake to release the prey and preventing further injury to the snake. Prey usually flee after being struck, and succumb to the venom a distance away from the snake. At this point, the snake will leave its ambush position to go find its meal. Our recordings have revealed, however, that rattlesnakes do not always strike and release. Especially with mice-prey, snakes strike and hold onto the rodent, and then injest it right away. Check out the video below:
Long ago in the days of my youth, I was once a wee Girl Scout. I enjoyed the camping trips and cross-stitching, but most of all I enjoyed learning about awesome animals (much like I do today). In order to give back to the community that inspired me, last month I gave a presentation to my little brother's Boy Scout troop. The boys in this troop live near undeveloped California foothills on which they hike often. More likely than not, they will at some point encounter a California snake. The goal of my presentation was to inform them how to identify California snakes (venomous vs. non-venomous), what to do when there is an encounter, and how to avoid/handle getting bit.
The fifth-grade boys in this troop were such a pleasure to talk to (much more fun than the undergrads I teach). They were very excited to ask and answer questions, participate in the group activities I developed, and they were all very respectful. As a treat, I brought in live snakes for them to look at (Rosy Boa, California Kingsnake, Long-nosed Snake, and Northern Pacific Rattlesnake), and I "tubed" the rattlesnake so that they could safely view and touch the rattle. Although the parents were initially uneasy about the tubing process, their fear subsided after they saw how docile the snake can be. To my delight, the children thought my presentation was the coolest thing in the world. Hopefully, I instilled in them a respect for these beautiful creatures that live in their backyards.
Looking at the Rosa Boa, Kingsnake, and Long-nose
Answering some of the boys' questions
Letting the boys touch the tail and rattle of "Mr. Cuddles"
Even the fathers got into it (too bad none of the moms were interested)
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